The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
In most modern automatic transmissions, hydraulic assemblies are filled and exhausted to engage and disengage various clutches and brakes to connect or release various gear components to selectively achieve a plurality of forward speeds or gear ratios and reverse.
One of the long recognized means of improving inter-ratio gear shifts, and one upon which there is much current emphasis, is to increase the speed of a shift, that is, to reduce the time between release of the currently engaged clutch(es) or brake(s) and engagement of the clutch(es) or brake(s) associated with the selected, new gear ratio.
One of the ways to increase shift speed is to increase fluid pressure and flow by increasing the size of the pump within the transmission. Any increase in pump size is accompanied by increased energy consumption and thus reduced overall efficiency of the transmission. Although important, compromising the efficiency of the transmission for shift events that occur during a small fraction of its operating time is not a readily acceptable tradeoff.
The present invention is directed to a device which provides improved shift speeds without the performance compromises accompanying prior solutions.